Abstract：Objective To investigate the value of chromosome karyotype analysis and single nucleotide microarray (SNP-array) in prenatal diagnosis of high-risk pregnant fetuses. Methods A retrospective study was conducted among 1 317 high-risk pregnant women and fetuses with prenatal diagnosis indication.The pregnant women were 17-48 years old, and the gestational ages were 17-34 weeks.Analysis on G banding karyotype and single nucleotide microarray (SNP-array) technique were performed, chromosome results and pregnancy outcomes were collected and analyzed. Results Among 1317 fetal chromosomes, there were 44 cases (3.3%) of karyotype polymorphism, 152 cases (11.5%) of karyotype abnormality, and 241 cases (18.3%) of SNP-array abnormality.There was significant differences between the two tests.There were 270 cases (20.5%) of chromosomal abnormalities using both G banding karyotype and SNP-array technique, and there was statistically significant differences with the detection rate of karyotype abnormalities.There were 123 cases (9.3%) with abnormal karyotype and SNP-array, 110 cases (9.8%) with abnormal karyotype, and 31 cases (2.9%) with abnormal karyotype.After excluding the interference of other indicators, the incidence of fetal karyotype and SNP-array abnormality was the highest in the isolated non-invasive high-risk group.Among the two types of combined indicators, fetal karyotype and SNP-array abnormality rate were highest in the elderly high-risk group with only non-invasive combination.The incidence of trisomy 21 was positively correlated with age (P=0.037).Among the adverse pregnancy history, the group with isolated abortive history had the highest rate of abnormal fetal karyotype, and the group with other adverse pregnancy history combined with positive soft ultrasound index had the highest rate of abnormal SNP-array.The chromosomal abnormalities were highest in fetuses with isolated NF thickening detected by SNP-ARRAY, followed by isolated long bone shortening and isolated lateral ventricular dilation.When the number of ultrasound abnormalities increased, the rate of karyotype and SNP-array abnormalities increased with the exclusion of other indicators but only ultrasound abnormalities, and the difference was statistically significant. Conclusion The incidence of trisomy 21 is positively correlated with age, Indication of non-invasive high risk, history of embryo arrest, short bone length, NF thickening and lateral ventricle dilation suggest increased risk of chromosomal abnormalities.The possibility of chromosomal abnormalities cannot be ruled out by intracardiac hyperechoic foci.Comprehensive pedigree analysis family after parental verification is still very important in genetic counseling.Karyotype analysis combined with SNP-ARRAY technology can improve the detection rate of chromosomal abnormalities.It's complementary to conduct karyotype and SNP-array analysis which would provide more accurate analysis for chromosomal abnormalities.Genetic counseling and reproductive guidance would benefit from the combined test and it is the preferred prenatal diagnosis program for fetuses of high-risk pregnant women.
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